984 EXPERIMENT STATION RECORD. 



but until recently the fruiting form had not been recognized. A recent investigation 

 showed the parasite to be Diplodia opuntix, first collected on Opuntia nana, in North- 

 ern Italy. The injury caused by the fungus is sometimes severe, the black minute, 

 wart-like outgrowths often covering a considerable area and the surrounding tissue 

 becoming discolored. 



Constitutional diseases of fruit trees, A. G. Campbell {Jour. Dept. Agr. Vic- 

 toria, 3 {1905), No. 6, pp. 463-465). — Brief descriptions are given of a number of 

 diseases of apples and apricots, which, so far as known, are not due to the presence 

 of any parasitic growth. 



The diseases described are watercore, bitter pit, and crinkle, a name given a rather 

 serious disease of the apple, in which the cells just beneath the skin, particularly 

 about the calyx, die and collapse, causing a sunken, discolored area. Some varieties 

 seem especially subject to this disease, the Rome Beauty being particularly liable to 

 this trouble. The disease of apricots described under the name smudge is character- 

 ized by the death of the cells in large irregular patches, over which the skin sinks, 

 leaving dark blotches on the surface. 



For the successful treatment of most of these troubles attention should be paid to 

 the proper cultivation of the trees, drainage, fertilizers, etc. 



Black spot canker and black spot apple rot, W. H. Lawrence {Jour. Mycol, 

 11 {1905), No. 78, pp. 164, 165). — The black spot canker fungus (Macrophoma curvi- 

 spora), like the bitter rot fungus, causes a disease of both the tree and fruit. It 

 differs, however, from bitter rot in that the canker stage does by far the greater 

 amount of injury. This stage has become very prevalent in certain parts of Brit- 

 ish Columbia, Oregon, and Washington, causing considerable loss. 



In January, 1903, the author noticed numerous decaying apples among stored 

 fruit, in which a few pustules were present in decaying areas, and later the epider- 

 mis overlying each pustule split, exposing a mass of creamy white spores. These 

 spores were identical with those previously recognized as typical of the black spot 

 canker fungus except that they were slightly larger. Inoculation experiments were 

 carried on to determine the relation of the canker and the rot, and it was found that 

 the fungus is parasitic in the bark and sapwood of the trunk and branches and also 

 on the stored fruit of the cultivated apple. 



The first indication of the presence of the disease in the fruit is a slight discolora- 

 tion of the flesh of the apple just beneath the epidermis. The flesh becomes a light 

 brown color and as more becomes involved the color changes to a deep brown. The 

 epidermis takes on a corresponding change of color, and the decaying spots become 

 depressed, dry, and leathery. In many cases the decaying areas are found near the 

 basin and calyx ends of the. fruit, being associated with codling moth burrows, 

 bruises, etc., but more than 50 per cent of the specimens examined showed that the 

 fungus entered directly through the epidermis of the fruit. 



Moisture and temperature were found to exert marked influence on the develop- 

 ment of the rot. In cool, dry weather the spots increase in size, but few pustules 

 are developed. During cool, damp weather an abundance of pustules is formed. 

 The tendency for certain varieties of fruit to decay more rapidly than others was 

 observed. 



A technical description of the fungus on both the tree and the fruit is given, based 

 upon the author's observations. 



Pear blight, cause and prevention, R. I. Smith ( Ga. Bd. Ent. Bui. 18, pp. 109- 

 126, pis. 2). — According to the author, pear blight in 1905 caused an unusual amount 

 of injury in both pear and apple orchards, in some localities practically destroying 

 the crop, while in others from 50 to 75 per cent of the blossoms were destroyed by 

 the form of the disease known as blossom blight. By special arrangement with this 

 Department cooperative experiments are being carried on in the nature of demonstra- 

 tion work to show the possibility of controlling this disease. 





